Setting device for a vehicle having a mechanically adjustable part, and method for operating the setting device

ABSTRACT

A setting device for a vehicle having a mechanically adjustable part in which a sensor assigned to the mechanically adjustable part generates sensor signals corresponding to the positions of the part. An initial range of the sensor values is assigned to an inoperative position of the part and covers the varying initial positions of the part. An evaluation device stores a longer constant signal in the initial range as an intermediate value. A longer constant sensor signal is compared with the intermediate value after the initial range is exceeded and after the subsequent return into this range. If it is established that both values are approximately of the same magnitude, the evaluation device stores this value as an initial value. As a result, the inoperative position of the part is reliably verified without the use of additional auxiliary components or steps.

This is a nationalization of PCT/IB01/01972, filed Oct. 22, 2001 andpublished in German.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a setting device for a motor vehicle with amechanically adjustable component and a process for operating thesetting device.

2. Description of the Related Art

It is typical in automobiles to couple a setting element, designed, forexample, as a foot lever, with a sensor, which detects the angularposition of the lever. The position signal of the lever is adjustedafter installation into the automobile, in that in a stop position ofthe foot lever an auxiliary signal is set by way of an external signalinput, or in that the position of the sensor itself is adjustedmechanically. The signal level, pending at the sensor in this instant,is then stored as the output signal and subtracted or compared in asubsequent operation. The reliability of the process can hardly beguaranteed according to automobile aspects. It is possible duringsubsequent operation of the motor vehicle that the geometry of the leverunit changes, for example, due to increasing bearing play, by means ofdeformations or in the event of a repair. Even the sensor, designed, forexample, as a rotary potentiometer or Hall sensor, can change itscharacteristics through wear and contamination, for example, with iceparticles. The properties of the electronic components will also vary inoperation due to aging and environmental influences, a factor that canresult automatically in a signal drift.

Conventional adaptive learning systems cannot be applied here, since theactuating profiles of the signals are a function of both the driver andthe traffic situation, such as an uncontrolled long dwell period in aspecific position. Furthermore, known algorithms cannot measure theshort-term zero point changes, such as those that occur, for example,after a repair.

The DE 3612904 A discloses a process for the tolerance compensation of aposition sensor signal, wherein the neutral position of the component ismonitored during the operation of the motor vehicle. In this respect themeasured values of an upper or a bottom stop are stored. Should one ofthese end values be exceeded during operation, the new measured value isstored as the new end value. This feature has the drawback that anactual drift of the neutral position toward the medium range cannot bedetected at all.

The invention is based on the problem of eliminating the adjustment costand increasing the functional reliability.

SUMMARY OF THE INVENTION

This problem is solved by means of the setting device for a motorvehicle in accordance with the present invention, the setting deviceincluding a mechanically adjustable component and a sensor whichmeasures the positions of the component and which is connected to anelectronic evaluating unit. A neutral position of the component can bedefined as the starting position, where the values of the sensor signalsthat correspond to the neutral position can be stored in the evaluatingunit as the initial value, where the neutral position of the componentcan be monitored as the motor vehicle is operating, and where as thesensor signals deviate significantly in the neutral position from theinitial value, the value of the current sensor signals can be stored asthe new initial value. According to the present invention, theevaluating unit recognizes a setting cycle, and can store a prolongedstationary dwell position of the component in an initial range of theneutral position. In addition, the departure from the initial range andthe approximately exact return into the stored stationary dwell positionand the prolonged dwelling therein can be stored as the actual neutralposition. Owing to the constant monitoring of the neutral positionduring operation, shifts of the signal level in the stop position can bedetected and corrected. A subsequent adjustment by expert personnel isno longer necessary. A special advantage lies in the fact that fewerrequirements have to be imposed on the stability, quality and assemblyof the setting device in order to guarantee its function.

A shift in the neutral value can be recognized reliably in bothdirections. Owing to the principle of repeating an initial value in aprolonged dwell position, it is possible to verify the neutral positionwith high certainty. It is also conceivable to fix the starting positionat the instant that the vehicle electronics is switched on. If, however,at this instant, for example, the clutch pedal was actuated, the resultis a misinterpretation with a corresponding malfunction of the operatingsystem. In addition, the signal displacements would not be detectable inoperation due to temperature variations. Since it is almost impossibleto hit and hold a free floating position precisely multiple times insuccession, it can be assumed with high certainty that at least a singlerepetition of a holding position within an initial range of the sensorsignals represents the actual starting position. Thus, by means of thisscheme the starting position is, in fact, detected dynamically, but notaffected by vibrations, which occur, for example, in automobiles.

Advantageous embodiments of the invention include design of thecomponent as an operating element with the sensor and at least parts ofthe evaluating unit being combined into a common module connected to ahousing of the operating element. By means of this further development,the setting device can be prepared and installed as a largely autonomoussystem without the need for any further tuning measures.

The operating element may further be provided with a resetting devicewhich, upon release of the operating element, moves it into the startingposition. Such a resetting device guarantees in a simple manner theneutral position.

The operating element may also be designed as a spring-loaded swinglever, in particular as a foot lever, with the sensor being designed asan inductive distance sensor for detecting the angular positions of theswing lever. This further development provides an operating device,which can be produced easily with high functional reliability and can beinstalled into an automobile. A coil of the inductive sensor can befastened, for example, to a pedal housing; and a metal part, grasped bythe coil, can be fastened to a foot lever. Related control electronicsare also fastened to the pedal housing and combined with the coil toform a module, which can also contain the evaluating electronics. Theinductive sensor detects the distance to the metal part and thus alsothe angular position of the foot lever.

The present invention further includes a process for operating a settingdevice in which the position of a mechanical component is detected by asensor coupled to an electronic evaluating unit. The method includes thesteps of assigning a threshold value to sensor signals to determine astarting position of the component, storing the threshold value and aninitial sensor signal value corresponding to the starting position inthe evaluating unit, and assigning the sensor signals having valuesbelow the threshold value to an initial range which corresponds to anallowable range of the component starting position. The processcontinues by defining an operating cycle by points at which the sensorvalues exceed the threshold value and subsequently return into theinitial range, and detecting a signal level of the sensor continuouslyor in narrow time intervals and comparing the signal level with thethreshold value. A sensor signal value which is below the thresholdvalue and which is constant over a minimum time duration is recognizedas an intermediate value and stored. The signal level with theintermediate value is compared with the initial value upon the sensorsignal value exceeding and then dropping below the threshold value and,in response to the sensor signal deviating from the initial value andremaining constant at the intermediate value over the minimum timeduration, the sensor signal is stored as a new initial value. Thesetting device may be operable within an automobile, and the startingposition of the component may be monitored during operation of theautomobile and redefined upon adequate deviation.

In determining the initial value, the degree of verification can beincreased even more, when, after another repetition of the exact neutrallevel, the output signal is recognized and stored. Such a multiplerepetition follows, for example, upon actuation of the clutch pedal in astarting phase.

BRIEF DESCRIPTION OF THE DRAWINGS

One embodiment of the invention is depicted in the drawing and isexplained below in detail.

FIG. 1 is schematic drawing of a partial side view of a pedalarrangement of an automobile with a distance sensor in a startingposition.

FIG. 2 depicts the parts, according to FIG. 1, in another functionalposition.

FIG. 3 is a curve diagram of the sensor values as the position of thepedal arrangement, according to FIG. 1, changes.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

According to FIG. 1, a mechanically adjustable component in the form ofa foot lever 1, serving as an operating element, is disposed in ahousing 5 so as to pivot about a pedal axis 2. Said housing can beinstalled into the foot space of an automobile. Above the foot lever 1there is a stationarily mounted coil element 3, which induces anelectromagnetic alternating field aimed in the direction of the footlever 1. The coil element 3 is a part of a module 6, which is fastenedto the housing and which is fastened to the housing 5 and which containsa control and evaluating electronic unit for the coil element.

Fastened to the foot lever 1, which is made, for example, of glass fiberreinforced plastic, there is a metal part 4, which together with thecoil element forms an inductive sensor and whose distance to the coilelement 3 changes as a function of the tilt position of the foot lever1. This brings about a corresponding change in the inductive resistanceof the coil element 3, a factor that results in a corresponding changein the measurable lost power of the coil element 3. The metal part 4,which is made of bent sheet metal, exhibits a convex cam-like curvature,whose contour is shaped in such a manner that the output signals of thesensor vary approximately in proportion to the angular position of thefoot lever 1.

The metal part exhibits a flectional contour, which is easy to produce,and can be connected to the foot pedal with little effort by insertinginto a casting mold for the foot lever. Therefore, this part of thesensor incurs almost no additional cost when subsequently installed intothe pedal space. In the illustrated starting position, the foot leverrests against a stop 8 of the housing 5 against the force of a resetspring 7 and, in so doing, assumes a neutral position, whose sensorvalue represents a corresponding initial value. One end of the metalpart is closely adjacent to the coil element and has a correspondinglystrong impact on its electromagnetic alternating field.

According to FIG. 2, the foot lever swings into a functional position,in which the distance to the coil element 3 is significantly enlarged.The inductive resistance of the coil element has changedcorrespondingly. In a directly coupled converter (not illustrated) thesensor values can be converted into output signals and can be processedin an electronic evaluating unit of the module 6.

FIG. 3 reproduces the curve of the sensor values during one operatingcycle, where t denotes the one time axis and s the axis of the sensorvalues. A threshold value sw, which is stored in the evaluating unit 9(FIG. 1), defines an initial range sr of the sensor values, within whichthe initial value can vary. A past initial value sp is stored in theevaluating unit. On the left hand side of the curve the foot lever is inthe stop position, according to FIG. 1. The sensor value s lies heresignificantly above the stored past initial value sp. Since the settingdevice, provided with a time element, does not exhibit any additionalsensor, for example, in the form of an end probe for detecting the stopposition, it assumes in the sensor value, which is constant over adefined minimum duration tm, below the threshold value sw a new initialvalue, which it stores as the temporary intermediate value st.

In the subsequent phase the foot lever 1 is swung out of its startingposition into the functional position, shown in FIG. 2, where the sensorvalues s clearly exceed the threshold value sw. After the foot lever hasreturned into the starting position, shown in FIG. 1, the sensor valuess reach in the right hand side of the curve exactly the amount of theintermediate value st, which remains constant over the specified minimumduration tm. The evaluating unit 9 compares this value with theintermediate value st. Upon adequate agreement between the two valuesand significant deviation from the stored initial value sp, theevaluating unit stores the intermediate value st as the new initialvalue spn for the neutral position of the foot lever 1 (FIG. 1).

Such a setting device and such an adjustment procedure can be appliednot only to operating elements of a motor vehicle, but also to othersetting and drive devices with cyclic sequences, for example in acarburetor or an injection system. The verification of the neutralposition through exact repetition renders additional evaluations, forexample, of probe positions or the current pickup of control drivessuperfluous. A special advantage lies in the fact that the device canwork with the related sensor totally independent of other variables, afactor that makes it possible to largely separate the differentmeasurement and control devices of the motor vehicle.

The invention being thus described, it will be apparent that the samemay be varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be recognized by one skilled in the art areintended to be included within the scope of the following claims.

1. A setting device for a motor vehicle with a mechanically adjustablecomponent, said setting device comprising: a sensor that measurespositions of the component, with a neutral position of the componentbeing defined as a starting position; said component designed as anoperating element provided with a reset device which, upon release ofsaid operating element, moves said operating element into said startingposition; and an electronic evaluating unit, connected to said sensorand receiving sensor signals, a sensor signal value that corresponds tothe neutral position being stored in said electronic evaluating unit asan initial value, the neutral position of the component being monitoredas the motor vehicle is operating and, when the sensor signals deviatesignificantly in the neutral position from the initial value, a currentsensor signal value being stored as a new initial value; said evaluatingunit recognizing a setting cycle and storing a prolonged stationarydwell position of the operating element in an initial range of theneutral position and storing a departure from the initial range, and anapproximately exact return into the stored stationary dwell position andthe prolonged dwelling therein, as the actual neutral position.
 2. Thesetting device, as claimed in claim 1, wherein the operating element andthe sensor and at least parts of the evaluating unit are combined into acommon module and are connected to a housing for the operating element.3. The setting device, as claimed in claim 1, wherein the operatingelement is designed as a spring-loaded swing lever, and the sensor,designed as an inductive distance sensor, detects angular positions ofsaid swing lever.
 4. The setting device, as claimed in claim 3, whereinthe operating element is a foot lever.
 5. A process for operating asetting device in which the position of a mechanical operating elementis detected by a sensor coupled to an electronic evaluating unit, themethod comprising the steps of: assigning a threshold value to sensorsignals to determine a starting position of the operating element, saidoperating element having a reset device; storing said threshold valueand an initial sensor signal value corresponding to said startingposition in the evaluating unit; assigning the sensor signals havingvalues below the threshold value to an initial range which correspondsto an allowable range of said component starting position; defining anoperating cycle by points at which the sensor values exceed thethreshold value and subsequently return into the initial range;detecting, by said evaluating unit, a signal level of the sensorcontinuously or in narrow time intervals and comparing the signal levelwith the threshold value; recognizing a sensor signal value which isbelow the threshold value and which is constant over a minimum timeduration, as an intermediate value and storing said intermediate value;comparing the signal level with the intermediate value and the initialvalue upon the sensor signal value exceeding and then dropping below thethreshold value; storing, in response to the sensor signal deviatingfrom the initial value and remaining constant at the intermediate valueover the minimum time duration, the sensor signal as a new initialvalue; and said reset device moving said operating element into saidstarting position upon release of said operating element.
 6. The processas claimed in claim 5, wherein the setting device is operable within anautomobile, and the starting position of the operating element ismonitored during operation of the automobile and is redefined uponadequate deviation.